Where backpressures can be expected to occur in a plumbing system, protection
against direct cross connections may be increased by the use of a
Under Condition 1, what action is taken when a drinking water sample is found to
a. Rejection of the system.
b. Increased surveiIlance and investigation, followed by emergency disinfection if
Flushing entire system, followed by emergency disinfection.
d. Increasing chlorine dosage and residual.
In the space to the left of each of the components of a water supply system Iisted
below, insert the number of the sanitary defect Iisted in the right-hand column that
is more likely than the others to occur in that type of system.
a. Surface water source.
(1) Water and sewer Iines laid in same trench.
b. Ground water source.
(2) Livestock watering in stream.
(3) Improper disinfection after repairs.
d. Distribution system.
(4) Rain barrels not covered.
(5) Contamination from privy located nearby.
Water may become contaminated as an _______________________ of a
widespread chemical attack rather than as a result of a direct attack on the water
A drastic lowering of the pH value of water is indicative that a ________________
A sudden increase in the chlorine demand in indicative that an
_________________________ agent is present.